Prediction of Motor Function Recovery after Subcortical Stroke: Case Series of Activation PET and TMS Studies

OBJECTIVE: To examine whether the pattern of brain activation induced by a motor task and the motor responses to transcranial magnetic stimulation (TMS) have prognostic implications for motor recovery after stroke. METHOD: Ten patients with first-ever subcortical stroke (55.7±17.3 years, 5 ischemic and 5 hemorrhagic) underwent 2 FDG PET studies under different conditions (1: rest, 2: activation with a specific motor task) at 37.7±25.2 days after stroke. The regions showing more than a 10% increase in glucose metabolism on subtraction images during activation and rest were considered to be significantly activated. Cortical excitability of intracortical inhibition (ICI) and intracortical facilitation (ICF) were assessed using the TMS from both abductor pollicis brevis muscles within 7 days of PET scans. Recovery of motor function was assessed at the point of the neurological plateau. RESULTS: The presence of a motor response at the plegic site to TMS and normal intracortical inhibition, and facilitation patterns in the unaffected hemisphere were found to be related to good recovery. An association between an ipsilesional activation on PET and good motor recovery was also observed, but this was significantly weaker than that between TMS measured cortical excitability and motor recovery. CONCLUSION: Integrity of the ipsilesional corticospinal pathway, normalized contralesional intracortical excitability, and task-related activation in the ipsilesional hemisphere were found to predict post-stroke motor recovery significantly.